Add a mechanism to sanitize options.

This simplifies usage of the Scour module while avoiding any compatibility issues that might be caused by adding/removing/renaming options.

scour/scour.py

@@ -2866,8 +2866,9 @@ def serializeXML(element, options, ind = 0, preserveWhitespace = False):
 # input is a string representation of the input XML
 # returns a string representation of the output XML
 def scourString(in_string, options=None):
-   if options is None:
+   # sanitize options (take missing attributes from defaults, discard unknown attributes)
-      options = _options_parser.get_default_values()
+   options = sanitizeOptions(options)
+
    getcontext().prec = options.digits
    global numAttrsRemoved
    global numStylePropsFixed
@@ -3289,6 +3290,18 @@ def generateDefaultOptions():
    return Struct(**d)
 
 
+
+# sanitizes options by updating attributes in a set of defaults options while discarding unknown attributes
+def sanitizeOptions(options):
+   optionsDict = dict((key, getattr(options, key)) for key in dir(options) if not key.startswith('__'))
+
+   sanitizedOptions = _options_parser.get_default_values()
+   sanitizedOptions._update_careful(optionsDict)
+
+   return sanitizedOptions
+
+
+
 def start(options, input, output):
 
    start = walltime()